"We apologize for the issues our customers have experienced as a result of an incident on the Network Solutions DNS," the company wrote on Facebook. "We're in the process of restoring services, and we appreciate your patience as we work toward resolution."

The DNS is a distributed address book for websites, translating domain names such as idg.com into an IP address that can be called into a Web browser. In the past few months, hackers have targeted companies that register domain names and their partners.

A successful DNS hijacking attack can cause thousands of Web surfers to a high-profile website to be redirected to another site even though they've typed in or browsed to the correct domain name.

Avira, a security company affected by the attacks two weeks ago, said hackers gained access to its Network Solutions account via a fake password-reset request. Claiming responsibility was a group calling itself the "Kdms Team," which also attacked the hosting provider LeaseWeb about two days before.

In a separate problem, Network Solutions said Monday some customers could not send email after it was blacklisted by a security company, Trend Micro, and other anti-spam services.